In some orthopaedic surgical procedures, such as a total knee replacement procedure, ligament balancing devices (commonly known as ligament balancers) may be used to balance the surrounding soft tissue (i.e., ligaments) of a patient's joint. For example, in a total knee replacement procedure, ligament balancing may be performed to ensure a generally rectangular shaped extension gap and a generally rectangular shaped flexion gap at a predetermined joint force value between the patient's natural or prosthetic proximal tibia and the patient's natural or prosthetic distal femur.
To do so, a ligament balancer may be used to measure the medial and lateral joint forces and the medial and lateral gap displacements when the patient's leg is in extension (i.e., the patient's tibia is positioned at about 0 degrees relative to the patient's femur) and in flexion (i.e., the patient's tibia is positioned at about 90 degrees relative to the patient's femur). In either extension or flexion, if the medial and lateral gap displacements are not approximately equal (i.e., do not form a generally rectangular shaped joint gap) at the predetermined joint force value, ligament release may be performed to equalize the medial and/or lateral gap displacements.